Dendritic polyetherketone and heat-resistant blend of PVC with the same

ABSTRACT

A hyperbranched polyetherketone and a heat-resistant blend of polyvinylchloride with the same. The polyethereketone is synthesized by self-polycondensation of 3,5-bis[4-[(2,3,4,5,6-pentafluorophenyl)carbonyl]phenoxy]-4-hydroxbenzophenone or 3,5-difluoro-4-hydroxybenzophenone, and then substituting 50 to 80 mole % of fluorine atoms present in the side chains and ends of the PEK molecule by polar groups. In addition, a blend of polyvinylchloride can be manufactured using the hyperbranched polyetherketone by a melt blending technique applicable for industrial purpose at a temperature of 180 to 120° C., and thus the blend of polyvinylchloride with the polyetherekentone can be applied to high temperature end-use products such as hot water pipes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a polyetherketone (PEK) and aheat-resistant blend of polyvinylchloride (PVC) with the same, and moreparticularly, to a dendritic or hyperbranched PEK which exhibitsmiscibility with PVC and allows for melt blending with PVC, and aheat-resistant blend of PVC with the PEK.

2. Description of the Related Art

PVC, the most common type of polymer in use, has a broad range ofapplications, for example, pipes, soft films for packing food, fibers,interior articles, and the like. However, PVC has a low glass transitiontemperature (Tg) and a low heat distortion temperature (HDT), whichrestricts the applications of PVC at a high-temperature range. Forexample, a commercial PVC exhibits a glass transition temperature ofabout 85° C. Thus, it would be highly desirable and commerciallyadvantageous to improve the heat-resistance of PVC and thereby providethe PVC with higher temperature end-use applications, such as hot waterpipes.

To meet this need, research into a technique for manufacturing linearpolymers which exhibit a high degree of miscibility with PVC and offerhigh glass transition temperatures and blends of PVC with the same hasbeen conducted. Most of linear polymers synthesized to satisfy this needfurther have polar groups at the backbone of common linear polymers.

For example, U.S. Pat. No. 4,698,390 teaches heat-resistant blends ofPVC containing a linear polycarbonate, the glass transition temperatureof which has been increased by adding sulfonic groups to the backbone ofthe polycarbonate. However, the problem with this PVC blend lies in theuse of a solution blending method which cannot be applicable to massproduction systems for commercial purpose. As another example,heat-resistant blend of PVC with polar linear polyarylates has beensuggested by S. -Y. Kwak et al., in an article entitled “Effect ofMolecular Structure of Polyarylates on the Compatibility inPolyarylate/PVC blends, Journal of Applied Polymer Science, 70, 2173,1998. However, in this disclosure a solution blending method has beenadopted rather than the melt blending method which is commerciallypracticable for the heat-resistant blends of PVC.

The difficultly in applying the melt blending method to prepare PVCblends is based on the following. First, PVC has a specific hierarchystructure and includes microcrystallites which serve to provide forphysical crosslinks within the structure, so that its temperature rangeof melt processing is restricted, for example, to a temperature of 180to 210° C. Second, for high temperature end-use applications of PVC, forexample, for use of PVC in making hot water pipes, it is required toblend PVC with linear polymers having glass transition temperaturesgreater than or equal to 160° C. In addition, when the melt blendingtechnique is applied to blend PVC with a linear polymer having such ahigh glass transition temperature, melt blending temperatures should be70 to 100° C. higher than the glass transition temperature of the linearpolymer added, i.e., in the range of 230 to 260° C. to allow for easymelt blending. The reason is because the linear polymer has muchentanglements in the melt state. As a result, PVC which exhibits weakthermal stability deteriorates at the high temperature.

SUMMARY OF THE INVENTION

In view of the above, it is an object of the present invention toprovide a hyperbranched polyetherketone (PEK) which has a glasstransition temperature (Tg) above 160° C. and offers a high degree ofmiscibility with polyvinylchloride by melt blending at a relatively lowtemperature of 180 to 210° C. within a short period of time.

It is another object of the present invention to provide aheat-resistant PVC blend with the hyperbranched PEK, which is applicableto high temperature end-use products such as hot water pipes.

The first object of the present invention is achieved by a PEKsynthesized by self-polycondensation of3,5-bis[4-[(2,3,4,5,6-pentafluorophenyl)carbonyl]phenoxy]-4-hydroxybenzophenonehaving the formula (1)

Another embodiment of the PEK according to the present invention issynthesized by fluorine substitution reaction from PEK polymerized from3,5-difluoro4′-hydroxybenzophenone having the formula (2)

Preferably, 50 to 80 mole % of fluorine atoms present in the molecularstructure of the PEK polymerized from3,5-difluoro-4′-hydroxybenzophenone having the formula (2) hereinaboveare substituted by polar groups having the formula (3)

—O—A—CN  (3)

wherein A represents

or alkylene groups of 1 to 3 carbon atoms, n has a value of from 0 to 2,and m has a value of 0 or 1, which allows for easy melt blending withPVC within a short period of time at relatively low temperatures.

Preferably, in the formula (3) A is

—CH₂—, —CH₂CH₂—, —CH₂CH₂CH₂—, —CH(CH₃)— or —C(CH₃)₂—.

Preferably, the degree of branching of the PEK synthesized from themonomer of formula (1) is in the range of 0.4 to 0.6.

The second object of the present invention is achieved by a blend of PVCcomprising: one of the previously mentioned PEKs in a ratio of 10 to 50percent by weight of the total blend; and PVC in a ratio of 90 to 50percent by weight of the total blend.

Preferably, the blend of PVC is manufactured by melt blending. Also, themelt blending may be carried out at a temperature of 180 to 210° C. Theblend of polyvinylchloride has a single glass transition temperature of105° C. or more in the differential power curve obtained by differentialscanning calorimetry.

The hyperbranched PEK according to the present invention has a highglass transition temperature greater than or equal to 160° C., and canbe uniformly blended with PVC by melt blending at relatively lowtemperatures within a short period of time. Also, the hyperbranched PEKensures that melt blending thereof with PVC is practicable forindustrial use and does not cause deterioration of PVC, and thus the PVCblend with the PEK can be efficiently used in manufacturing hightemperature end-use applications such as hot water pipes.

BRIEF DESCRIPTION OF THE DRAWING

The above objects and advantages of the present invention will becomemore apparent by describing in detail preferred embodiments thereof withreference to the attached drawing in which:

FIG. 1 illustrates the molecular structure of a hyperbranchedpolyetherketone (PEK) according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In synthesizing a preferred embodiment of polyetherketone according tothe present invention,3,5-bis[4-[(2,3,4,5,6-pentafluorophenyl)carbonyl]phenoxy]-4-hydroxybenzophenone(BPFBP) having the formula (1) hereinabove is initiallyself-polycondensated. In the self-polycondensation reaction, acondensation reaction between fluorine atoms and hydroxy groups occursto form ether bonds and thus a polymer. The condensation reactionbetween fluorine and hydroxy groups takes place at one or two points perBPFBP repeating unit. If this condensation reaction occurs at one pointper BPFBP repeating unit, a polyetherketone (PEK) having the formula (4)will be obtained.

Meanwhile, if the condensation reaction between flourine and hydroxygroups occurs at two points per BPFBP repeating unit, a polyetherketon(PEK) having the formula (5) will be obtained.

As can be noted from comparison between the formulas (4) and (5), thehigher the occurrence of condensation reaction at two points per therepeating unit, the greater the number of branches in the produced PEK,resulting in hyperbranched PEKs.

Next, the hyperbranched PEK is reacted with aromatic or aliphatic cyanoalcohol compounds having the formula (6) to substitute approximately 50to 80 mole % of fluorine present in the molecular structure of the PEKby the polar groups having the formula (3) hereinabove.

—O—A—CN  (6)

wherein A represents

or alkylene groups of 1 to 3 carbon atoms, n has a value of from 0 to 2,and m has a value of 0 or 1. Preferably, A is selected from the groupconsisting of

—CH₂—, —CH₂CH₂—, —CH₂CH₂CH₂—, —CH(CH₃)— and —C(CH₃)₂—.

The substitution reaction is carried out to ensure a high degree ofmiscibility and ease of melt blending with PVC, and higher glasstransition temperature of the PVC blend with the PEK. The improvedmiscibility with PVC is due to polar-polar interaction between the polargroups substituted for fluorine and the polar PVC. Also, if it werepossible for 100 mole % of fluorine in the PEK to be substituted by thepolar groups described above, PEKs having the formulas (4) and (5) couldbe converted to PEKs having the formulas (7) and (8), respectively, bythe substitution reaction.

In actual reaction systems, although excess reagent given by the formula(6) is added, it is impossible to replace 100 mole % of fluorine withthe polar groups. However, the degree of substitution of fluorine mustbe controlled by adjusting the equivalent of the reagent added so as tomake the inventive PEK have sufficient miscibility and ease of meltblending with PVC. If the degree of substitution is less than 50 mole %,the polarity of PEK obtained may not be sufficient to provide adesirable miscibility and ease of melt blending with PVC. Meanwhile,since a degree of substitution above 80 mole % cannot improve themiscibility and ease of melt blending with PVC more and more, it isinefficient to increase the degree of substitution to be above 80 mole%.

Another embodiment of PEK according to the present invention issynthesized by end-group substitution reaction of the PEK polymerizedfrom 3,5-difluoro-4′-hydroxybenzophenone (DFHBP) having the formula (2).In the self-polycondensation reaction of DFHBP, a condensation reactionbetween fluorine atoms and hydroxy groups occurs to form ether bonds andthus a polymer. The condensation reaction between fluorine and hydroxygroups takes place at one or two points per DFHBP repeating unit. Ifthis condensation reaction occurs at one point per DFHBP repeating unit,a polyetherketone (PEK) having the molecular structure of the formula(9) will be obtained.

Meanwhile, if the condensation reaction between fluorine and hydroxygroups occurs at two points per DFHBP repeating unit, a polyetherketone(PEK) having the molecular structure of the formula (10) will beobtained.

As can be noted from comparison between the formulas (9) and (10), thehigher the occurrence of condensation at two points per the repeatingunit, the greater the number of branches in the produced PEK, resultingin highly hyperbranched PEKs.

Next, the hyperbranched PEK is reacted with aromatic or aliphatic cyanoalcohol compounds having the formula (6), which is used in the synthesisof the PEK described previously, to substitute approximately 50 to 80mole % of fluorine present in the molecular structure of the PEK by thepolar groups having the formula (3) hereinabove.

If it were possible for 100 mole % of fluorine in the PEK to besubstituted by the polar groups described above, PEKs having theformulas (9) and (10) could be converted to PEKs having the formulas(11) and (12), respectively, by the substitution reaction, respectively.

In actual reaction systems, although excess reagent given by the formula(6) is added, it is impossible to replace 100 mole % of fluorine withthe polar groups. However, the degree of substitution of fluorine mustbe controlled by adjusting the equivalent of the reagent added so as tomake the inventive PEK have sufficient miscibility and ease of meltblending with PVC.

FIG. 1 illustrates the molecular structure of a hyperbranchedpolyetherketone (PEK) according to the present invention. As shown inFIG. 1, the PEK, which is obtained through self-polycondensation ofmonomers each having AB₂ (herein, A represents hydroxy groups and Brepresents fluorine), has a hyperbranched semi-globular structure. Inparticular, the hyperbranched structure of PEK is comprised of linearstructural units 1, branched structural units 3 and end structural units5. Due to the many branched structural units 3 of the PEK, entanglementof molecular chains is almost non-existent, compared to linear polymers,and provides the PEK with a low melt viscosity compared to linear PEKshaving similar molecular weights, which assures ease of melt blendingwith PVC at relatively low temperatures, that is, in the range oftemperatures melt processing of PVC is practicable. In addition, it hasbeen found that the PEK according to the present invention can be easilyblended with PVC by melting in a PVC processing temperature range from180 to 210° C. within a short period of time. Accordingly, aheat-resistant blend of PVC can be easily produced by melt blending on acommercial scale without deterioration of PVC.

Also, the PEK according to the present invention has many fluorinatedend structural units 5, and thus, based on the reactivity of thefluorine, the molecular chain of the PEK can take many polar groups,which increases the glass transition temperature and the miscibilitywith polar PVC. To produce the higher degree of miscibility with PVC andthe higher glass transition temperature of PEK, in the synthesis of thePEK according to the present invention, 50 to 80 mole % of fluorinepresent in the side chains and ends of the PEK molecule are substitutedby aromatic or aliphatic cyano groups which induce polar-polarinteraction with chlorine groups of PVC. In addition, the heat-resistantblend of PVC with the PEK exhibits a high glass transition temperatureand a high heat distortion temperature (HDT), so that it is applicableto high temperature end-use products such as hot water pipes. Also, itssuperior miscibility with PVC assures thermal and mechanical stabilityafter use for a longer period of time.

Preferably, the degree of branching of the PEK synthesized from themonomer of formula (1) according to the present invention is adjustedfrom 0.4 to 0.8. If the degree of branching is below 0.4, the amount ofreactive fluorine atoms decreases, and thus the degree of substitutionof polar cyano groups must be increased to above 80 mole % to assure ahigher glass transition temperature and better miscibility with PVC.Also, it is unpractical to polymerize the hyperbranched is polymer to adegree of branching above 0.8.

The present invention will be described in greater detail by means ofthe following examples. The following examples are for illustrativepurposes and not intended to limit the scope of the invention.

EXAMPLE 1

The present example provides illustration of the synthesis of3,5-bis[4-[2,3,4,5,6-pentafluorophenyl)carbonyl]phenoxy]-4-hydroxybenzophenone(BPFBP) having the formula (1) illustrated above.

Stage 1. Synthesis of 3,5-difluoro-4-methoxybenzophenone

A 3-necked flask was charged with 30 ml of 1,2-dichloroethane, 7.6 g(70.0 mmol) of anisole, and 9.7 g (73.0 mmol) of aluminum chloride(AlCl₃), a catalyst for Friedel-Crafts acylation reaction. While purgingthe flask at room temperature with an argon gas, a solution containing10.0 g (56.6 mmol) of 3,5-difluorobenzoylchloride dissolved in 15 ml of1,2-dichloroethane was added dropwise to the flask and left for 14 hoursfor reaction. Subsequently, 20 ml of deionized water was added to theflask and stirred for 15 hours. The reaction product was poured into 200ml of deionized water and washed three times, each time with 100 ml ofmethylene chloride, to extract 3,5-difluoro-4-methoxybenzophenone. Thesolvent was evaporated from the reaction product to give the3,5-difluoro4-methoxybenzophenone in a yield of 97%.

Stage 2. Synthesis of 3,5-diphenoxy-4-methoxybenzophenone

This stage was for introducing phenol to the obtained3,5-difluoro-4-methoxybenzophenone by nucleophilic aromatic substitutionreaction. A 3-necked flask was charged with 6.0 g (24.2 mmol) of3,5-difluoro-4-methoxybenzophenone, 9.0 g (95.8 mmol) of phenol, 9.0 g(65.2 mmol) of potassium carbonate (K₂CO₃) as a basic catalyst, 50 ml ofN-methylpyrrolidone (NMP) and 20 ml of toluene, and heated to refluxtoluene for 2 hours at 150° C. while pulsing the flask with an argongas. Under the reflux, water was removed and collected in a Dean-Starktrap.

Then, the reaction temperature was raised to 200° C. for furtherreaction for 4 hours. After the reaction was complete, the reactionmixture was poured into 600 ml of deionized water and washed with etherto extract 3,5-diphenoxy-4-methoxybenzophenone. The ether was evaporatedfrom the 3,5-diphenoxy-4-methoxybenzophenone and dried to give the3,5-diphenoxy-4-methoxybenzophenone in a yield of 72%.

Stage 3. Synthesis of3,5-bis[4-[2,3,4,5,6-pentafluorophenyl)carbonyl]phenoxy]-4-methoxybenzophenone

This stage was for introducing reactive fluorine atoms to the obtained3,5-diphenoxy-4-methoxybenzophenone to obtain3,5-bis[4-[2,3,4,5,6-pentafluorophenyl)carbonyl]phenoxy]-4-methoxybenzophenone.A 3-necked flask was charged with 5.0 g (12.6 mmol) of the3,5-diphenoxy-4-methoxy benzophenone, 6.5 g (48.7 mmol) of AlCl₃ as acatalyst for Friedel-Crafts acylation reaction, and 30 ml of1,2-dichchloroethane. While purging the flask at room temperature withan argon gas, a solution containing 6.0 g (26.0 mmol) ofpentafluorobenzoylchloride dissolved in 15 ml of 1,2-dichloroethane wasadded dropwise to the flask and left for 4 hours for reaction.Subsequently, 20 ml of deionized water was added to the flask andstirred for 15 hours. The reaction product was poured into 300 ml ofdeionized water and washed four times, each time with 100 ml ofmethylene chloride, to extract3,5-bis[4-[(2,3,4,5,6-pentaflurophenyl)carbonyl]phenoxy]-4-methoxybenzophenone.The solvent was evaporated from the reaction product to give the3,5-bis[4-[(2,3,4,5,6-pentaflurophenyl)carbonyl]phenoxy]-4-methoxybenzophenonein a yield of 83%.

Stage 4. Synthesis of BPFBP

This stage was for converting the methoxy group of the obtained3,5-bis[4-[(2,3,4,5,6-pentaflurophenyl)carbonyl]phenoxy]-4-methoxybenzophenoneto hydroxy group to synthesize the BPFBP. A 3-necked flask was chargedwith 5.0 g (6.4 mmol) of the3,5-bis[4-[(2,3,4,5,6-pentaflurophenyl)carbonyl]phenoxy]-4-methoxybenzophenone,50 ml of 48% HBr and 100 ml of glacial acetic acid, and heated to reactfor 15 hours under reflux. Then, the flask was cooled and excess glacialacetic acid was evaporated. The reaction product was poured into 400 mlof deionized water and washed four times, each time with 100 ml ofether. Then, the solvent was evaporated from the reaction product, whichresulted in a mixture of the unreacted3,5-bis[4-[(2,3,4,5,6-pentaflurophenyl)carbonyl]phenoxy]-4-methoxybenzophenoneand the desired BPFBP. The mixture was dissolved in a 0.1N -sodiumhydroxide solution and filtered to remove the precipitants. Then, a 0.1N-hydrochloric acid was added dropwise to the remaining solution,filtered and then dried to give the desired monomer BPFBP in a yield of72%.

EXAMPLE 2

The present example provides an illustration of the synthesis of3,5-difluoro-4′-hydroxybenzophenone (DFHBP) having the formula (2)illustrated above.

Stage 1. Synthesis of 3,5-difluoro4-methoxybenzophenone

A 3-necked flask was charged with 30 ml of 1,2-dichloroethane, 7.6 g(70.0 mmol) of anisole, and 9.7 g (73.0 mmol) of AlCl₃, a catalyst forFriedel-Crafts acylation reaction. While purging the flask at roomtemperature with an argon gas, a solution containing 10.0 g (56.6 mmol)of 3,5-difluorobenzoylchloride dissolved in 15 ml of 1,2-dichloroethanewas added dropwise to the flask and left for 4 hours for reaction.Subsequently, 20 ml of deionized water was added to the flask andstirred for 15 hours. The reaction product was poured into 200 ml ofdeionized water and washed three times, each time with 100 ml ofmethylene chloride, to extract 3,5-difluoro4-methoxybenzophenone. Thesolvent was evaporated from the reaction product to give the3,5-difluoro4-methoxybenzophenone in a yield of 97%.

Stage 2. Synthesis of DFHBP

This stage was for converting the methoxy group of the obtained3,5-difluoro-4-methoxybenzophenone to hydroxy group to synthesize theDFHBP. A 3-necked flask was charged with 13.6 g (54.9 mmol) of the3,5-difluoro-4-methoxybenzophenone, 60 ml of 48% HBr and 90 ml ofglacial acetic acid, and heated to react for 15 hours under reflux.Then, the flask was cooled and excess glacial acetic acid wasevaporated. The reaction product was poured into 400 ml of deionizedwater and washed three times, each time with 150 ml of ether. Then, thesolvent was evaporated from the reaction product, which resulted in amixture of the unreacted 3,5-difluoro-4′-methoxybenzophenone and thedesired DFHBP. The mixture was dissolved in a 0.1N-sodium hydroxidesolution and filtered to remove the precipitants. Then, a0.1N-hydrochloric acid was added dropwise to the remaining solution,filtered and then dried to give the desired monomer DFHBP in a yield of72%.

EXAMPLE 3

The present example provides an illustration of theself-polycondensation of the BPFBP having the formula (1) illustratedabove.

A 3-necked flask was charged with 10 ml of NMP, 3.0 g (3.9 mmol) ofBPFBP, 0.2 g (8.7 mmol) of sodium as a catalyst, and 0.1 g (0.45 mmol)of 15-crown-5. The flask was heated under reflux for 6 hours at 120° C.while purging with an argon gas, for the self-polycondensation reaction.After the reaction was complete, the reaction product was poured into500 ml of deionized water to precipitate, and stirred at roomtemperature for 5 hours. Then, the precipitants were filtered, washedtwice with 500 ml of methanol, and dried to give a hyperbranched PEKhaving reactive fluorine atoms in the side chains and ends of themolecule thereof, which has a degree of branching of 0.6, a numberaverage molecular weight of 16,000, a polydispersity of 2.2, and a glasstransition temperature of 138° C.

The degree of branching, which indicates the ratio of branchedstructural units present in the molecular structure, was determined by¹⁹F NMR spectroscopy and calculated using the following equation, assuggested by D. Hoelter et al. in an article entitled “Degree ofBranching in Hyperbranched Polymers”, Acta Polymer., 48, 30, 1997.${{degree}\quad {of}\quad {branching}} = \frac{\quad^{19}F\quad {peak}\quad {area}\quad {of}\quad {end}\quad {structural}\quad {units}}{\begin{pmatrix}{{\quad^{19}F\quad {peak}\quad {area}\quad {of}\quad {end}\quad {structural}\quad {units}} +} \\{\quad^{19}F\quad {peak}\quad {area}\quad {of}\quad {linear}\quad {structural}\quad {units}}\end{pmatrix}}$

Also, the molecular weight of the PEK was determined by means of gelpermeation chromatography (GPC) and linear polystyrene standards wereused for calculation.

EXAMPLE 4

The present example provides an illustration of theself-polycondensation of the DFHBP having the formula (2) illustratedabove.

A 3-necked flask was charged with 20 ml of NMP, 15 ml of toluene, 3.0 g(14.1 mmol) of DFHBP and 2.8 g (20.0 mmol) of K₂CO₃ as a basic catalyst.The flask was heated to reflux toluene for 3 hours at 150° C. whilepurging with an argon gas. Under the reflux, water was removed andcollected in a Dean-Stark trap. Then, the reaction temperature wasraised to 200° C. at a rate of 5° C./min for further reaction for 3hours. After the reaction was complete, the reaction product was pouredinto 800 ml of deionized water to precipitate, and stirred at roomtemperature for 5 hours. Then, the precipitants were filtered, washedtwice with 500 ml of methanol, and dried to give a hyperbranched PEKhaving reactive fluorine atoms in the side chains and ends of themolecule thereof, which has a degree of branching of 0.5, a numberaverage molecular weight of 23,000, a polydispersity of 2.5, and a glasstransition temperature of 160° C.

EXAMPLE 5

This example provides an illustration of the substitution of fluorineatoms present in the side chains and ends of PEK molecule obtained inExample 3 by polar groups which improves miscibility and ease of meltblending with PVC.

A 3-necked flask was charged with 20 ml of NMP, 3.0 g of PEK obtained inExample 3, 3.0 g of one of the aromatic or aliphatic cyano alcoholcompounds listed in Table 1, and 2.8 g (20.0 mmol) of K₂CO₃ as a basiccatalyst. The flask was heated at a rate of 2° C./min while purging withan argon gas. The mixture was reacted for 3 hours and the heatingtemperature was varied in the range of 180 to 200° C. depending on thetype of cyano alcohol compound used. After the reaction was complete,the reaction product was poured into 800 ml of deionized water toprecipitate, and stirred at room temperature for 5 hours. Then, theprecipitants were filtered, washed twice with 500 ml of methanol, anddried to give a hyperbranched PEK in which some of the reactive fluorineatoms present in the side chains and ends of the molecule weresubstituted by the aromatic or aliphatic cyano groups. The numberaverage molecular weight, the degree of substitution by polar cyanogroups, the polydispersity and the glass transition temperature for eachPEK are shown in Table 1.

Table 1 shows that the substitition of some of the fluorine atomspresent in the PEK molecule by aromatic cyano groups increases the glasstransition temperature of the ultimate polymer product by about 33-43°C. compared to that before the substitution. For reference, the glasstransisiton temperature of the PEK from Example 3 before thesubstitution was 138° C. This is because the effect of raising the glasstransition temperature by the presence of aromatic groups and polargroups is more notable than the effect of lowering the glass transitiontemperature by the formation of ether bonds.

However, the substitution of some of the fluorine atoms present in thePEK molecule by aliphatic cyano groups barely changes the glasstransition temperature relatiave to before the substitution. This isbecause the rise in glass transition temperature due to the presence ofpolar groups is offset by the decrease in glass transition temperaturedue to the presence of ether bonds and aliphatic groups.

TABLE 1 Degree of Number average Glass transition Cyano compoundsubstitution molecular weight temperature reacted with PEK (%) (g/mol)Polydispersity (Tg, ° C.) 2-Cyanophenol 61  9,000 1.8 171 3-Cyanophenol70 11,000 1.4 177 4-Cyanophenol 66 10,000 1.7 181 4-Hydroxy- 78 15,0001.6 175 benzylcyanide 3-Hydroxy- 73  9,000 1.5 148 propionitrileLactonitrile 68  7,000 1.7 133 Acetone 62  8,000 1.5 129 cyanohydrine

EXAMPLE 6

The present example provides an illustration of the substitution offluorine atoms present in the side chains and ends of the PEK moleculeobtained in Example 4, which improves miscibility and ease of meltblending with PVC.

The substitution reaction of Example 5 was followed except that the PEKobtained in Example 4 was used instead of the PEK obtained in Example 3.The number average molecular weight, the degree of substitution by polarcyano groups, the polydispersity and the glass transition temperaturefor each PEK are shown in Table 2.

As shown in Table 2, the change in the glass transition temperature ofeach PEK according to the type of polar groups shows a similar patternto that shown in Table 1.

TABLE 2 Degree of Number average Glass transition Cyano compoundsubstitution molecular weight temperature reacted with PEK (%) (g/mol)Polydispersity (Tg, ° C.) 2-Cyanophenol 68 16,000 1.6 176 3-Cyanophenol77 21,000 1.5 183 4-Cyanophenol 66 20,000 1.7 184 4-Hydroxy- 81 22,0001.9 177 benzylcyanide 3-Hydroxy- 77 19,000 1.6 166 propionitrileLactonitrile 63 13,000 1.4 155 Acetone 66 15,000 1.3 148 cyanohydrine

EXAMPLE 7

The present example provides an illustration of the ease of meltblending of PVC with the PEKs obtained in Examples 5 and 6, and thesuperior thermal properties of PVC blends with the same.

Commercially available PVC (having a number average molecular weight of20,000, a polydispersity of 1.5, a glass transition temperature of 83°C., obtained by suspension polymerization), and either the PEK ofExample 5 or the PEK of Example 6 were mixed in a ratio of 9:1, 8:2,7:3, 6:4 and 5:5 by weight of the total mixture (of about 40-50 g), andmelt blended in an internal mixer (manufactured by Haake PolyLab Co.).As a result, all samples were uniformly blended at a temperature of 190to 200° C. within about 450 seconds, and showed a single glasstransition temperature in the differential power curve obtained bydifferential scanning calorimetry (DSC). Thus, it can be concluded thatthe PEKs of Examples 5 and 6 can be easily and uniformly mixed with PVCby melt blending.

On the other hand, it has been found that the thermal properties of PVCblends vary depending on the mixing ratio between PEK and PVC, and thetype of substituted cyano groups. For the PVC blends with the PEK ofExample 5, the substitution by aromatic cyano groups showed a glasstransition temperature of 121 to 133° C. and a softening temperature(Vicat) of 117 to 129° C., while the substitution by aromatic cyanogroups showed a glass transition temperature of 106 to 117° C. and asoftening temperature of 101 to 112° C.

For the PVC blends with the PEK of Example 6, the substitution byaromatic cyano groups showed a glass transition temperature of 126 to134° C. and a softening temperature of 120 to 130° C., while thesubstitution by aromatic cyano groups showed a glass transitiontemperature of 112 to 125° C. and a softening temperature of 106 to 121°C.

Briefly, the PVC blends with PEKs of Examples 5 and 6 according to thepresent invention exhibit considerably better thermal properties thanpure PVC, and various heat-resistant materials can be produced byadjusting the mixing ratio of PEK and PVC and the type of polar groupsintroduced to PEK.

As described above, the PEKs according to the present invention ensureeasy melt blending with PVC at relatively low temperatures, resulting inPVC blends having excellent heat-resistance which are applicable inmanufacturing hot water pipes. The PEKs according to the presentinvention can extend the processing temperature range of PVC to a highertemperature limit compared to conventional PVC.

While this invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention as defined by the appended claims.

What is claimed is:
 1. A polyetherketone synthesized byself-polycondensation of 3,5-difluoro-4′-hydroxybenzophenone having theformula (I)

wherein 50 to 80 mole % of fluorine atoms present in the molecularstructure of the polyetherkeone are substituted by polar groups havingthe formula (II) —O—A—CN  (II) wherein A represents

 or alkylene groups of 1 to 3 carbon atoms, n has a value of from 0 to2, and m has a value of 0 or
 1. 2. The polyetherketone of claim 1,wherein A is selected from the group consisting of

—CH₂—, —CH₂CH₂—, —CH₂CH₂CH₂—, —CH(CH₃)— and —C(CH₃)₂—.
 3. A blend ofpolyvinylchloride comprising: a polyetherketone according to claim 1 ina ratio of 10 to 50 percent by weight of the total blend; andpolyvinylchloride in a ratio of 90 to 50 percent by weight of the totalblend.
 4. The blend of polyvinylchloride of claim 3, wherein the blendis manufactured by melt blending.
 5. The blend of polyvinylchloride ofclaim 4, wherein the melt blending is carried out at a temperature of180 to 210° C.
 6. The blend of polyvinylchloride of claim 3, wherein theblend has a single glass transition temperature of 105° C. or more in adifferential power curve obtained by differential scanning calorimetry.